An authentication token is a device given to a user to assist the user in proving his or her identity electronically. The authentication token may generate one-time passwords. For example, the authentication token may generate a code periodically based on an initialization vector and timing information. To illustrate the use of an authentication token, suppose that to access a secured resource (e.g., a virtual private network, a secured network site, etc.), a user is requested to supply a username and a password. However, the username and password may be compromised, potentially through no fault of the user. In addition, if the user is requested to provide a code generated by the authentication token, it may be assumed that the user has the authentication token in his or her physical possession and is not a malicious user who has gained access only to the username and password.